This project is studying the genetic controls on the catecholamine biosynthetic enzymes in the adrenal glands of inbred mouse strains. Two related sublines of the Balb/c strain are being investigated. These mice differ by two-fold in their levels of tyrosine hydroxylase, dopamine beta hydroxylase and phenylethanolamine N-methyl transferase. Our previous work has shown that each of the enzymes is under genetic control; that each enzyme is regulated by a single gene; that enzyme phenotypes are inherited together; and that one of the enzymes is regulatd at the gene level by a protease which controls the rate of enzyme degradation. The current project continues that work. We are investigating the biochemical mechanisms whereby the controlling genes regulate the level of each of the enzymes. Our operating hypothesis is that the genetic control is expressed on the rate of enzyme degradation. Highly sophisticated immunochemical and radiolabelling techniques are employed to address this issue.